Drafting device



March 1927. 2 v v. KVASNICKA DRAFTING DEVICE Filed May 29, 1922 Patented Mar. 29, 1927.

vAcLAv KvAsnIcKA, or PRAGUE, cznonosLovAmA.

DRAFTING DEVICE.

Application filed May 29, 1922. $erial No. 584,463.

This invention relates to a device for drawing parallel and angular-1y projected lines with a 'l"square.

T-squares are known which have the longitudinal member pivotally secured to the transverse head member for the purpose of enabling the drawing of parallel and angular lines at selected angles to such head member. These T-squares, however, have the disadvantage that the draftsman, especially in working on large drawing boards, must hold both the longitudinal and transverse members in order to. avoid errors in drawing parallel lines, especially at the end of the T-square.

Furthermore, with known T-squares, it is only possible to reach the inner portion adjacent to the transverse member, whereas, the corners of the drawing board cannot be reached by the end of the T-square.

It is, therefore, the principal object of this invention to provide adrafting device which obviates the aforesaid disadvantages and which permits the drawing of parallel and angularly projected lines at any place on the drawing board with the aid of a comparatively short T-square.

Other objects of equal importance will become apparent from the specification and, claim forming a part hereof. The attached drawing illustrates a preferred embodiment of the invention.

In the illustrations, Figure 1 is a plan View of the device embodying my invention, and

Figure 2 is a cross section taken on line 22 of Figure 1. i

The device forming the subject matter of the invention comprises a rail K which normally extends between the longitudinal sides of the drafting board or table and may be of a greater length than the width of the drawing board on which it is intended for use. On the face 3 of the recessed straight edge of the rail K, is a slidably mounted comparative short T-square B, the transverse head member thereof being guided on said recessed strright edge. The longitudinal member of the T-square engages the inclined top surface of the rail K and also engages the top surface of the drawing board by virtue of the curvature in the blade B pro vided for in the flexibility of such blade.

The face 3 of the recessed portion of the rail K is provided with an aperture 7 and a plurality of additional apertures 9 extending longitudinally Within such recessed portion through which thumb tacks 10 may be inserted for the purpose of securing the rail on any part of the drawing on which it is used. The head member of the T-square B is provided with a longitudinal groove l at the bottom face thereof to provide clearance for the heads of the thumb tacks.

In using the device, one end of the rail K is fixed to the board by the insertion of a thumb tack 10 in the aperture 7 and after adjustment to the desired position, the rail K is securely fixed in such position by the insertion of an additional thumb tack 10 in any one of the apertures 9. This arrangement permits the T-square B to be very short and still enables a convenient and reliable drafting on any part of the board by reason of its portability, so that the use of additional triangles is reduced to a minimum.

The device, furthermore, has the advantage that in executing large drawings, the drawing paper does not need to be cut into sections and later pasted or otherwise secured together, but a roll of paper may be used and successive portions thereof may be fastened 011 the board and a long drawing executed by means of the device.

A further advantage in the use of the comparatively short T-square, such as provided in this invention, is the possible reduction in the number of errors which may occur in the use of long T-squares, particu larly in drawing long parallel or angular-1y projected lines.

I claim:

A device for drawing parallel lines on a drafting board, comprising a T-square having a head member and a longitudinal drawing blade, said head member having the up per face thereof disposed at an angle to the plane of the base thereof, an end portion on said blade extending over the upper face of said head or cross-member for rigid connection thereto and being disposed at an angle to the integral laterally extending drawing portion thereof, a guide rail for said head member comprising a body having an inclined upper surface extending longitudinally of said body and from one side to substantially the longitudinal center line thereof, a ledge integral with said inclined body portion extending longitudinally of said body below the elevated edge of the inclined upper surface, said ledge having a flat upper surface parallel with the bottom face of said body vfor the support of the under side of said head member, the inner face of said head member having sliding engagement with said elevated edge, and the upper inclined face of said head member and said inclined surface of said guide rail occupying a common plane, and the bottom face of the drawing portion of said blade being in plane alignment Withthe bottom of said guide rail.

In Witness whereof, I have hereunto subscribed my name this third day of May,

VACLAV KVASNIUKA. 

